Accuracy and Reliability of Functional Imaging in Assessing Instability of Lumbar Degenerative Spondylolisthesis

Accuracy and Reliability of Functional Imaging in Assessing Instability of Lumbar Degenerative Spondylolisthesis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Accuracy and Reliability of Functional Imaging in Assessing Instability of Lumbar Degenerative Spondylolisthesis Tomonori Morita, Arihiko Tsukamoto, Ryunosuke Fukushi, Shutaro Fujimoto, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7492640/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 05 Nov, 2025 Read the published version in European Spine Journal → Version 1 posted 11 You are reading this latest preprint version Abstract Purpose Surgical management of lumbar degenerative spondylolisthesis—whether decompression alone or combined with fusion—often relies on instability assessment with standing flexion–extension radiographs. However, these evaluations are influenced by low back pain and other factors, introducing variability into instability determination and surgical planning. Despite widespread use, the reproducibility of quantitative parameters remains unclear. This study evaluated the reproducibility of commonly used quantitative indicators from lumbar functional imaging. Methods We retrospectively analyzed 112 patients with L4–5 degenerative spondylolisthesis who underwent two sets of standing flexion–extension radiographs within six months. Five parameters were measured: Changes in lumbar lordosis during flexion [ΔLL(flex)], changes during extension [ΔLL(ext)], sagittal translation (ST), posterior opening (PO), and segmental angulation (SA). Instability was defined as ST ≥ 3 mm or ≥ 8% of the upper vertebral body width, PO ≥ 5°, or SA ≥ 20°, and diagnostic consistency was examined. Two raters independently assessed all radiographs. Intra- and inter-rater reliabilities were determined using intraclass correlation coefficients (ICC[ 1 , 1 ], ICC[ 2 , 1 ]). Bland–Altman analysis tested fixed and proportional bias. Results Diagnostic discrepancies between imaging sessions occurred in 25.0–27.7%. ΔLL(flex) showed poor intra-rater reliability (ICC = 0.23, 0.32), whereas ΔLL(ext) and PO demonstrated higher reliability. ST and SA yielded low ICC values. Inter-rater reliability was consistently good (ICC > 0.75), and no fixed or proportional bias was detected. Conclusion Variability in flexion influenced ST and SA, potentially affecting instability diagnosis. Standardized imaging protocols and clearer patient instructions are essential to improve diagnostic accuracy and reliability. Lumbar Instability Spondylolisthesis Lumbar spinal stenosis Radiography Functional imaging Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Degenerative spondylolisthesis occurs when one vertebra slips relative to the adjacent lower vertebra. Patients with this condition frequently experience leg and back pain and functional limitations, such as neurogenic intermittent claudication, due to lumbar spinal stenosis resulting from spondylolisthesis, disc bulging, ligamentous hypertrophy, and facet joint degeneration. Surgical treatment is generally recommended for patients with persistent pain despite conservative management[ 1 ]. For surgical planning, evaluation of vertebral stability is critical, as it guides the choice between decompression alone and decompression with fusion. Various imaging techniques have been proposed to assess segmental instability in patients with lumbar spondylolisthesis. Wood et al. reported that flexion–extension radiographs in the lateral decubitus position reduced muscle contraction and increased translation[[ 2 ]. Luk et al. identified erect flexion and prone traction as the most clinically relevant views[ 3 ]. D’Andrea et al. suggested the supine–prone position for dynamic examinations[ 4 ]. Zhou et al. demonstrated that supine and decubitus lateral radiographs produced greater reductions in olisthesis than extension radiographs, and that combining flexion with supine or decubitus views revealed greater intervertebral mobility than conventional flexion–extension imaging[ 5 ]. Instability has also been assessed by comparing upright lateral radiographs with sagittal MRI or CT scans obtained in the supine position[ 6 , 7 ]. Issa et al. showed that seated lateral radiographs are suitable alternatives to standing flexion radiographs and that instability can be detected using preoperative MRI combined with a single seated lateral radiograph[ 8 ]. However, because imaging techniques and diagnostic thresholds vary across institutions, treatment strategies remain inconsistent. Defining segmental spinal instability has therefore remained a clinical and scientific challenge for nearly a century. Currently, conventional standing flexion–extension radiographs are the most widely used method for evaluating intervertebral instability; however, low back and leg pain may restrict the range of flexion and extension, complicating efforts to obtain radiographs with consistent bending angles across examinations[ 9 , 10 ]. It has been reported that light physical assistance during flexion radiographs significantly increased flexion and, consequently, sagittal translation (ST), posterior opening (PO), and segmental angulation (SA), leading to higher rates of instability detection[ 11 ]. These findings suggest that the degree of flexion and extension may vary depending on the patient's condition at the time of imaging, potentially introducing variability into instability assessment and influencing diagnostic outcomes. Accurate evaluation of intervertebral instability requires achieving the maximal possible range of flexion and extension. Conversely, insufficient motion may underestimate instability. Measurements should also be consistent and reproducible regardless of pain or external factors. Nevertheless, few studies have systematically examined the reliability of lumbar flexion–extension radiographs in terms of measurement reproducibility. Given the clinical importance of reliable functional imaging in diagnosing spinal instability, this study aimed to investigate the reliability of commonly used radiographic parameters derived from standing lumbar flexion–extension radiographs. Materials and Methods Study design The retrospective observational study evaluated intra- and inter-rater reliabilities, as well as absolute reliability, of measurements obtained from lumbar flexion–extension radiographs used to assess spinal instability. A test–retest design was employed, analyzing repeated radiographs acquired within a 6-month interval. Patients We included 112 patients diagnosed with L4–5 degenerative spondylolisthesis who underwent multiple lumbar functional radiographs within a 6-month period between January 2012 and December 2022 at a single institution. The cohort comprised 43 males and 69 females, with a mean age of 70.0 ± 10.7 years (41–90 years). Mean patient height was 155.8 ± 8.9 cm (133.0–179.5 cm), mean weight was 61.3 ± 12.3 kg (25.0–96.5 kg), and mean body mass index was 25.2 ± 4.4 kg/m 2 (range, 11.8–39.2 kg/m 2 ). Exclusion criteria were prior thoracolumbar surgery, multilevel lumbar spondylolisthesis, retrolisthesis, ossification of the posterior longitudinal ligament, ankylosing spondylitis, and severe scoliosis. The L4–5 level was selected because it is the most frequently affected single level, prone to instability due to sagittally oriented facet joints and greater gravitational loading compared with other vertebrae[ 12 – 15 ]. The institutional review board approved the study protocol, and written informed consent was obtained from all participants. Radiographic measures Upright, flexion, and extension standing radiographs were obtained to evaluate lumbar instability. Before each examination, patients were instructed by the radiology technician to bend forward and backward to the maximum extent possible. Images were acquired using digital X-ray cassettes with a film–focus distance of 1.15 m. Changes in lumbar lordosis during forward flexion [ΔLL(flex)] were measured as the difference in lumbar lordosis between upright and flexion positions. Changes during extension [ΔLL(ext)] were determined by comparing extension and upright positions[ 16 ]. Additionally, ST, PO, and SA were also measured on functional radiographs (Fig. 1 ). ST was measured according to the method of Dupuis et al. expressed as both absolute values and percentages of the upper vertebral body width[ 17 ]. PO was measured on flexion radiographs using the method of Luk et al.[ 3 ]. The angle was defined as positive for kyphosis and negative for lordosis. SA was calculated as the difference in intervertebral angles between extension and flexion positions[ 18 ]. Statistical analysis Two independent raters evaluated each patient’s two sets of functional radiographs to measure ΔLL(flex), ΔLL(ext), ST, PO, and SA. Rater A was an experienced spine surgeon with 19 years of clinical practice (T.M.), and Rater B was an orthopedic surgeon with 3 years of experience (T.I.). Intervertebral instability was defined as ST ≥ 3 mm or ≥ 8% of the upper vertebral body width, PO ≥ 5°, or SA ≥ 20°[ 17 , 19 , 20 ]. Consistency of instability diagnosis was analyzed separately for each rater. Intra-rater reliability was assessed for each rater using ICC(1,1), based on the first and second radiographic sets. Inter-rater reliability was evaluated using ICC(2,1) from the first set of radiographs. Absolute reliability was examined with Bland–Altman analysis for both intra- and inter-rater comparisons[ 21 ]. Bland–Altman plots and limits of agreement (LoA) were used to assess measurement repeatability and agreement between raters. The minimal detectable change at the 95% confidence level (MDC 95 ) was calculated when no fixed or proportional errors were present, representing the smallest measurable difference beyond error. Fixed bias was determined by calculating the 95% confidence interval of the mean difference between measurements, with significance defined as p < 0.05 in paired t-tests. Proportional bias was evaluated using the Pearson correlation coefficient (r) between measurement means and differences; a significant correlation (p < 0.05) indicated proportional bias. All statistical analyses were performed using SPSS software (version 30; IBM Corp., Armonk, NY, USA), with statistical significance set at p < 0.05. Results Measurement values The values of ΔLL(flex), ΔLL(ext), ST, PO, and SA measured by the two independent raters are shown in Table 1 . Both Rater A and Rater B evaluated all 112 cases. Table 1 Measurement values of ΔLL(flex), ΔLL(ext), ST, PO, and SA. Rater A Rater B 1st imaging 2nd imaging 1st imaging 2nd imaging ∆LL(flex) 13.3 ± 9.3 11.7 ± 7.4 13.4 ± 9.0 13.8 ± 7.9 ∆LL(ext) 9.0 ± 5.7 9.2 ± 5.9 9.5 ± 6.3 9.0 ± 5.9 ST 2.4 ± 1.2 2.3 ± 1.2 2.5 ± 1.2 2.3 ± 1.4 PO -1.5 ± 4.2 -1.7 ± 4.7 -1.8 ± 4.3 -2.0 ± 4.0 SA 4.8 ± 2.9 4.4 ± 3.0 5.0 ± 3.2 5.5 ± 2.8 ΔLL(flex) Change in lumbar lordosis during forward flexion (°), ΔLL(ext) Change in lumbar lordosis during back extension (°), ST Sagittal translation (mm), PO Posterior opening (°), and SA Segmental angulation (°). Instability diagnosis Discrepancies in instability diagnosis between the two imaging sessions were observed in 28 cases (25.0%) for Rater A and 31 cases (27.7%) for Rater B (Fig. 2 ). Consistent diagnoses of instability across both sessions were made in 20 cases (17.9%) by Rater A and 24 cases (21.4%) by Rater B. Intra-rater reliabilities Intra-rater reliability results are summarized in Tables 2 and 3 . For Rater A, ΔLL(flex), ST, and SA demonstrated poor to low reliability [ICC(1,1) = 0.23, 0.53, and 0.37, respectively], indicating considerable intra-rater variability. PO showed good reliability [ICC(1,1) = 0.76], and ΔLL(ext) demonstrated moderate reliability [ICC(1,1) = 0.68]. Similar patterns were observed for Rater B, with ΔLL(flex), ST, and SA demonstrating low reliability [ICC(1,1) = 0.32, 0.35, and 0.31, respectively]. Bland–Altman plots (Fig. 3 ) indicated acceptable agreement between repeated measurements of ΔLL(flex) and ST by both raters. The MDC 95 analysis showed the greatest variability in ΔLL(flex). Table 2 Intra-rater reliability of Rater A for the measurements of ΔLL(flex), ΔLL(ext), ST, PO, and SA. Relative reliability Absolute reliability Fixed error Proportional error ICC(1,1) 95%CI Mean Diff 95%CI T value P value r P value SEM MDC 95 LoA ∆LL(flex) 0.23 0.047〜0.40 1.71 -0.29〜3.70 1.70 0.093 0.17 0.066 7.53 20.9 -19.2 ~ 22.6 ∆LL(ext) 0.68 0.57〜0.77 -0.19 -1.06〜0.68 -0.44 0.66 -0.046 0.63 3.28 9.09 -9.28 ~ 8.89 ST 0.55 0.40〜0.66 0.096 -0.12〜0.31 0.89 0.38 -0.059 0.53 0.81 2.25 -2.14 ~ 2.34 PO 0.76 0.67〜0.83 0.26 -0.33〜0.84 0.87 0.39 -0.16 0.10 2.19 6.07 -5.82 ~ 6.34 SA 0.37 0.20〜0.52 0.41 -0.21〜1.03 1.32 0.19 -0.033 0.73 2.34 6.49 -6.08 ~ 6.91 ICC Intraclass Correlation Coefficient, CI Confidence Interval, SEM Standard Error of Measurement, Mean Diff Mean Difference, LoA Limits of Agreement, MDC Minimal detectable change, r Correlation Table 3 Intra-rater reliability of Rater B for the measurements of ΔLL(flex), ΔLL(ext), ST, PO, and SA. Relative reliability Absolute reliability Fixed error Proportional error ICC(1,1) 95%CI Mean Diff 95%CI T value P value r P value SEM MDC 95 LoA ∆LL(flex) 0.32 0.15〜0.48 -0.41 -2.27〜1.44 -0.44 0.66 0.13 0.17 7.01 19.4 -19.8 ~ 19.0 ∆LL(ext) 0.69 0.58〜0.78 0.43 -0.46〜1.33 0.96 0.34 0.089 0.35 3.39 9.40 -8.95 ~ 9.82 ST 0.35 0.17〜0.50 0.24 -0.053〜0.52 1.62 0.11 -0.17 0.081 1.10 3.05 -2.78 ~ 3.26 PO 0.66 0.54〜0.75 0.24 -0.41〜0.88 0.73 0.47 0.092 0.34 2.42 6.71 -6.49 ~ 6.96 SA 0.31 0.13〜0.46 -0.49 -0.21〜1.03 -1.45 0.15 0.15 0.12 2.52 6.99 -7.46 ~ 6.49 Inter-rater reliabilities Inter-rater reliability results are presented in Table 4 . Statistical analysis revealed good inter-rater reliability [ICC(2,1) > 0.75] for all parameters. SEM values were generally higher than those obtained in the intra-rater analysis. Bland–Altman analysis demonstrated no fixed or proportional errors, a finding further supported by Fig. 4 , which showed no systematic bias between raters in ΔLL(flex) and ST measurements from the first imaging. Unlike intra-rater results, ΔLL(flex) demonstrated high inter-rater reliability. Table 4 Inter-rater reliability for the measurements of ΔLL(flex), ΔLL(ext), ST, PO, and SA. Relative reliability Absolute reliability Fixed error Proportional error ICC(2,1) 95%CI Mean Diff 95%CI T value P value r P value SEM MDC 95 LoA ∆LL(flex) 0.81 0.74〜0.87 -0.12 -1.17〜0.94 -0.22 0.83 0.058 0.54 4.00 11.1 -11.2 ~ 11.0 ∆LL(ext) 0.80 0.72〜0.86 0.46 -1.16〜0.25 -1.29 0.20 -0.17 0.076 2.67 7.40 -7.87 ~ 6.95 ST 0.79 0.70〜0.85 -0.10 -0.24〜0.048 -1.34 0.18 -0.10 0.27 0.56 1.55 -1.65 ~ 1.45 PO 0.83 0.76〜0.88 0.30 -0.16〜0.77 1.29 0.20 -0.012 0.90 2.67 7.40 -4.57 ~ 5.17 SA 0.79 0.71〜0.85 -0.18 -0.56〜0.19 -0.97 0.33 -0.17 0.069 1.41 3.91 3.72 ~ 4.08 Discussion Despite multiple randomized trials and meta-analyses, consensus remains lacking on whether decompression alone or decompression with fusion provides superior outcomes for degenerative lumbar spondylolisthesis[ 22 – 24 ]. This uncertainty is partly attributable to the absence of standardized imaging protocols and evaluation criteria for lumbar instability. The lack of a widely accepted, simple, and reproducible imaging method has hindered the development of statistically validated criteria based on postoperative clinical outcomes and radiographic findings. Currently, parameters such as ST, PO, and SA are used to evaluate lumbar instability. However, studies have demonstrated that these values may be markedly reduced when lumbar flexion is insufficient[ 2 , 8 , 11 ]. In conventional standing flexion–extension radiographs, patients are instructed to bend forward maximally. Nevertheless, many patients—particularly those experiencing pain or discomfort—struggle to achieve adequate flexion. In the absence of a defined endpoint, forward bending remains highly variable and dependent on patient effort. Against this backdrop, the present study evaluated the reproducibility and reliability of instability-related parameters derived from standard standing flexion–extension radiography, the most widely used functional imaging technique worldwide. To our knowledge, this is the first study to comprehensively assess the reliability of functional radiographic evaluations in this context. In this study, discrepancies in instability diagnosis between the two imaging sessions were identified in 28 cases (25.0%) by Rater A and in 31 cases (27.7%) by Rater B. Only 20 cases for Rater A and 24 cases for Rater B were consistently classified as unstable in both evaluations. These inconsistencies in diagnosis highlight concerns regarding the reproducibility and diagnostic accuracy of instability assessment using conventional flexion–extension radiographs. Without reliable evaluation of instability, establishing a sound basis for determining whether decompression alone or decompression with fusion is the appropriate surgical strategy remains difficult. Therefore, before considering surgical options, it is necessary to understand in detail the reproducibility and limitations of the widely used flexion–extension imaging method. Intra-rater analysis demonstrated that ΔLL(flex) had poor reliability, with an ICC(1,1) of 0.23 (95% CI: 0.047–0.40) for Rater A and 0.32 (95% CI: 0.15–0.48) for Rater B, indicating substantial measurement variability. Similarly, ST showed relatively low ICC(1,1) values of 0.53 for Rater A and 0.35 for Rater B, both insufficient for clinical reliability. In contrast, PO and ΔLL(ext) exhibited good and moderate reliability for Rater A and B. The higher reliability of PO may stem from its calculation based on a single measurement (the intervertebral angle in flexion), whereas parameters such as ΔLL(flex), ST, and SA depend on the difference between two measurements (flexion and extension), which increases compounded variability. The relatively greater reliability of ΔLL(ext) may also reflect the smaller range of motion and reduced pain or fear of falling associated with extension compared with flexion. For all parameters, neither fixed nor proportional bias was identified. T values were not statistically significant, and all correlation coefficients (r) were < 0.2, indicating that measurement errors were random rather than systematic and that no methodological bias was present in the measurement techniques. Notably, ΔLL(flex) demonstrated extremely wide LoA and large MDC 95 , suggesting that even a difference of approximately 20° may fall within the range of measurement variability. In contrast, inter-rater reliability analysis showed high consistency across all parameters. ICC(2,1) values for ΔLL(flex), ΔLL(ext), ST, PO, and SA exceeded 0.75, with narrow and stable 95% confidence intervals. Neither fixed nor proportional bias was identified, and the LoA and MDC 95 ranges were within clinically acceptable limits. These findings suggest that the measurement technique and procedures were well standardized, enabling consistent evaluation across raters. Of particular importance, although ΔLL(flex) and ST exhibited poor and relatively low intra-rater reliability, they demonstrated high inter-rater reliability. This suggests that the measurement technique is inherently robust and reproducible, and that variability is more likely attributable to patient-related factors—specifically, inconsistency in reproducing the same degree of flexion, variability in effort, and the absence of clear guidance on the extent of forward bending. Taken together, these findings indicate that the prevailing method of standing flexion–extension radiography has limited reliability, with substantial variability across imaging sessions. To establish dependable criteria for surgical decision-making in lumbar spondylolisthesis—specifically, whether decompression alone is sufficient or fusion is required—it is essential to develop a functional imaging protocol that incorporates clear, standardized instructions and ensures high reproducibility. This study has several limitations. First, the sample size was relatively small. Second, only one flexion and extension radiograph was obtained per session. In addition, patient-reported outcomes such as pain or other patient-centered assessments were not evaluated at the time of imaging. Conclusion This study demonstrated that instability parameters derived from standing lumbar flexion–extension radiographs exhibited variable intra-rater reliability, particularly for ΔLL(flex) and ST, whereas inter-rater reliability was consistently high across all parameters. These results suggest that the measurement technique is reproducible, but limitations of the imaging method—such as inconsistent flexion and the absence of a standardized endpoint—contribute substantially to variability between sessions. To enhance diagnostic accuracy and guide evidence-based surgical decision-making for lumbar degenerative spondylolisthesis, development of a standardized functional imaging protocol that reduces methodological variability is warranted. Declarations Funding The authors did not receive support from any organization for the submitted work. Consent Informed consent was obtained from all individual participants included in the study. Competing interests The authors declare no competing interests. Ethics approval All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Author Contribution TM conceptualized and designed the study; TM, AT, RF, SF, and TI collected the data; TM and HT performed the statistical analysis; TM wrote the initial draft of the manuscript; ME helped revise the manuscript; TY supervised this study; and AT performed validation of this study. All authors critically reviewed the manuscript and approved the final version. Acknowledgement We thank Izaya Ogon for their assistance while conducting this study and the editors for English language editing. Data Availability The datasets generated during and/or analyzed during the current study are not publicly available, but are available from the corresponding author on reasonable request. References Hennemann S, de Abreu MR (2021) Degenerative Lumbar Spinal Stenosis. Rev Bras Ortop (Sao Paulo) 56:9–17. 10.1055/s-0040-1712490 Wood KB, Popp CA, Transfeldt EE, Geissele AE (1994) Radiographic evaluation of instability in spondylolisthesis. 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Cite Share Download PDF Status: Published Journal Publication published 05 Nov, 2025 Read the published version in European Spine Journal → Version 1 posted Editorial decision: Revision requested 23 Sep, 2025 Reviews received at journal 14 Sep, 2025 Reviews received at journal 12 Sep, 2025 Reviewers agreed at journal 12 Sep, 2025 Reviews received at journal 10 Sep, 2025 Reviewers agreed at journal 09 Sep, 2025 Reviewers agreed at journal 06 Sep, 2025 Reviewers invited by journal 04 Sep, 2025 Editor assigned by journal 01 Sep, 2025 Submission checks completed at journal 01 Sep, 2025 First submitted to journal 30 Aug, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7492640","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":512302800,"identity":"2164d656-06a0-4c29-a30e-85a756d6507b","order_by":0,"name":"Tomonori Morita","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABFklEQVRIiWNgGAWjYJCCA0hsCTkIzQYmE3BqAeqRgGkxJkoLA5IWhsQGJC1YgW5778PDH2oY6vjFDh978HGPRfr89rNHN3woY5Dnb2B49gCLFrMzxw0OHDjGICE5Oy3dcMYzidwNZ/LSbs44x2A44wBDugE2LTfSgH5hY5AwuJ1jJs1zAKiFIcfsNm8bA+MGBoY0CZxa/iG0pMv3vzG7/beNwR6vloNtCC0JDDeAtjC2MSTi1HLmGMOBs30SkjNnp6VJzjggYbjhxru0mz3nJJJnHMbhl+NtzB8qvtnw80snH5P4cKBOXr4/99iNH2U2tv3tPWnYQgwKUBzAAxVh5knDrQMV8MAY7MeI1TIKRsEoGAXDGgAAzK5nKoTmvA0AAAAASUVORK5CYII=","orcid":"","institution":"Sapporo Medical University School of Medicine","correspondingAuthor":true,"prefix":"","firstName":"Tomonori","middleName":"","lastName":"Morita","suffix":""},{"id":512302801,"identity":"3360ab11-65a4-48b0-bf19-d414453ecde7","order_by":1,"name":"Arihiko Tsukamoto","email":"","orcid":"","institution":"Sapporo Medical University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Arihiko","middleName":"","lastName":"Tsukamoto","suffix":""},{"id":512302802,"identity":"d03eee8b-e04d-4e29-bdf6-02b6f2b8ca10","order_by":2,"name":"Ryunosuke Fukushi","email":"","orcid":"","institution":"Sapporo Medical University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Ryunosuke","middleName":"","lastName":"Fukushi","suffix":""},{"id":512302803,"identity":"fac878d9-71cc-4a72-aeac-e88aee2fbae5","order_by":3,"name":"Shutaro Fujimoto","email":"","orcid":"","institution":"Sapporo Medical University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Shutaro","middleName":"","lastName":"Fujimoto","suffix":""},{"id":512302804,"identity":"9c0d46f2-3ed6-4718-a043-fda205a2bd34","order_by":4,"name":"Makoto Emori","email":"","orcid":"","institution":"Sapporo Medical University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Makoto","middleName":"","lastName":"Emori","suffix":""},{"id":512302805,"identity":"bc25217e-1e30-481c-9be2-50452890348d","order_by":5,"name":"Hiroyuki Takashima","email":"","orcid":"","institution":"Hokkaido University","correspondingAuthor":false,"prefix":"","firstName":"Hiroyuki","middleName":"","lastName":"Takashima","suffix":""},{"id":512302806,"identity":"e982d6ac-e971-43a6-9633-095c23a25173","order_by":6,"name":"Tomohiro Izawa","email":"","orcid":"","institution":"Sapporo Medical University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Tomohiro","middleName":"","lastName":"Izawa","suffix":""},{"id":512302807,"identity":"5f806249-7d4c-4036-bca7-6062fa46c255","order_by":7,"name":"Toshihiko Yamashita","email":"","orcid":"","institution":"Sapporo Medical University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Toshihiko","middleName":"","lastName":"Yamashita","suffix":""},{"id":512302808,"identity":"cbed70e9-98d3-4039-a4ed-f1f2246d1ef7","order_by":8,"name":"Atsushi Teramoto","email":"","orcid":"","institution":"Sapporo Medical University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Atsushi","middleName":"","lastName":"Teramoto","suffix":""}],"badges":[],"createdAt":"2025-08-30 04:23:08","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7492640/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7492640/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00586-025-09539-9","type":"published","date":"2025-11-05T15:57:01+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":91023430,"identity":"153b3252-6d4f-4475-a4aa-06ba4121e6e4","added_by":"auto","created_at":"2025-09-10 19:15:02","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":6471153,"visible":true,"origin":"","legend":"\u003cp\u003eSpondylolisthesis measurement: Sagittal translation (ST) was assessed by measuring the distance between lines c and d on flexion (a) and extension (b) radiographs, calculating the difference (x−y), and expressing it as a percentage of the upper vertebral body width (w). Posterior opening (PO) was measured as the intervertebral angle on the flexion radiograph (−α), and segmentalangulation (SA) was calculated as the difference in intervertebral angles between the flexion and extension radiographs (β−α).\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7492640/v1/05bb48c86fe708994c3e5ff1.png"},{"id":91022821,"identity":"3e49dc91-dd67-45eb-91d8-518e2f6ed5af","added_by":"auto","created_at":"2025-09-10 19:07:02","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":192720,"visible":true,"origin":"","legend":"\u003cp\u003eGraphs showing discrepancies and consistency in instability diagnoses between the first and second imaging sessions. For Rater A, instability diagnoses were inconsistent in 28 cases (25.0%) and consistent in 20 cases (17.9%). For Rater B, discrepancies were observed in 31 cases (27.7%) and consistent diagnoses were made in 24 cases (21.4%).\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7492640/v1/99bdd3635f888e6c8fb6e856.jpeg"},{"id":91022825,"identity":"52bc862d-f46d-4576-8dde-c5aca493dec8","added_by":"auto","created_at":"2025-09-10 19:07:02","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":5620102,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Bland–Altman plot showing intra-rater agreement for ΔLL(flex) by Rater A (first vs. second imaging). (b) Bland–Altman plot showing intra-rater agreement for ΔLL(flex) by Rater B (first vs. second imaging). (c) Bland–Altman plot showing intra-rater agreement for ST by Rater A (first vs. second imaging). (d) Bland–Altman plot showing intra-rater agreement for ST by Rater B (first vs. second imaging). The x-axis indicates the mean of the paired measurements, and the y-axis shows their difference.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7492640/v1/b5c9ee05f6b195ec3dab3953.png"},{"id":91022364,"identity":"e3b2ac65-2a93-48d4-91bc-a37ec8a98b07","added_by":"auto","created_at":"2025-09-10 18:59:02","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":280285,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Bland–Altman plot of inter-rater agreement for ΔLL(flex) in the first imaging. (b) Bland–Altman plot of inter-rater agreement for ST in the first imaging. The x-axis represents the mean of the two measurements for each patient, and the y-axis represents the difference between the two measurements.\u003c/p\u003e","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7492640/v1/ae213bfbc70acb86ae32477e.jpeg"},{"id":95563929,"identity":"8f6fb28d-4d17-4b1d-bfe3-58145c42edd3","added_by":"auto","created_at":"2025-11-10 16:04:32","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":12120640,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7492640/v1/fea429db-0a6d-419f-996a-09fc10614b86.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Accuracy and Reliability of Functional Imaging in Assessing Instability of Lumbar Degenerative Spondylolisthesis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eDegenerative spondylolisthesis occurs when one vertebra slips relative to the adjacent lower vertebra. Patients with this condition frequently experience leg and back pain and functional limitations, such as neurogenic intermittent claudication, due to lumbar spinal stenosis resulting from spondylolisthesis, disc bulging, ligamentous hypertrophy, and facet joint degeneration. Surgical treatment is generally recommended for patients with persistent pain despite conservative management[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. For surgical planning, evaluation of vertebral stability is critical, as it guides the choice between decompression alone and decompression with fusion.\u003c/p\u003e\u003cp\u003eVarious imaging techniques have been proposed to assess segmental instability in patients with lumbar spondylolisthesis. Wood et al. reported that flexion\u0026ndash;extension radiographs in the lateral decubitus position reduced muscle contraction and increased translation[[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Luk et al. identified erect flexion and prone traction as the most clinically relevant views[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. D\u0026rsquo;Andrea et al. suggested the supine\u0026ndash;prone position for dynamic examinations[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Zhou et al. demonstrated that supine and decubitus lateral radiographs produced greater reductions in olisthesis than extension radiographs, and that combining flexion with supine or decubitus views revealed greater intervertebral mobility than conventional flexion\u0026ndash;extension imaging[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Instability has also been assessed by comparing upright lateral radiographs with sagittal MRI or CT scans obtained in the supine position[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Issa et al. showed that seated lateral radiographs are suitable alternatives to standing flexion radiographs and that instability can be detected using preoperative MRI combined with a single seated lateral radiograph[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. However, because imaging techniques and diagnostic thresholds vary across institutions, treatment strategies remain inconsistent. Defining segmental spinal instability has therefore remained a clinical and scientific challenge for nearly a century.\u003c/p\u003e\u003cp\u003eCurrently, conventional standing flexion\u0026ndash;extension radiographs are the most widely used method for evaluating intervertebral instability; however, low back and leg pain may restrict the range of flexion and extension, complicating efforts to obtain radiographs with consistent bending angles across examinations[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. It has been reported that light physical assistance during flexion radiographs significantly increased flexion and, consequently, sagittal translation (ST), posterior opening (PO), and segmental angulation (SA), leading to higher rates of instability detection[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. These findings suggest that the degree of flexion and extension may vary depending on the patient's condition at the time of imaging, potentially introducing variability into instability assessment and influencing diagnostic outcomes.\u003c/p\u003e\u003cp\u003eAccurate evaluation of intervertebral instability requires achieving the maximal possible range of flexion and extension. Conversely, insufficient motion may underestimate instability. Measurements should also be consistent and reproducible regardless of pain or external factors. Nevertheless, few studies have systematically examined the reliability of lumbar flexion\u0026ndash;extension radiographs in terms of measurement reproducibility. Given the clinical importance of reliable functional imaging in diagnosing spinal instability, this study aimed to investigate the reliability of commonly used radiographic parameters derived from standing lumbar flexion\u0026ndash;extension radiographs.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStudy design\u003c/h2\u003e\u003cp\u003eThe retrospective observational study evaluated intra- and inter-rater reliabilities, as well as absolute reliability, of measurements obtained from lumbar flexion\u0026ndash;extension radiographs used to assess spinal instability. A test\u0026ndash;retest design was employed, analyzing repeated radiographs acquired within a 6-month interval.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003ePatients\u003c/h3\u003e\n\u003cp\u003eWe included 112 patients diagnosed with L4\u0026ndash;5 degenerative spondylolisthesis who underwent multiple lumbar functional radiographs within a 6-month period between January 2012 and December 2022 at a single institution. The cohort comprised 43 males and 69 females, with a mean age of 70.0\u0026thinsp;\u0026plusmn;\u0026thinsp;10.7 years (41\u0026ndash;90 years). Mean patient height was 155.8\u0026thinsp;\u0026plusmn;\u0026thinsp;8.9 cm (133.0\u0026ndash;179.5 cm), mean weight was 61.3\u0026thinsp;\u0026plusmn;\u0026thinsp;12.3 kg (25.0\u0026ndash;96.5 kg), and mean body mass index was 25.2\u0026thinsp;\u0026plusmn;\u0026thinsp;4.4 kg/m\u003csup\u003e2\u003c/sup\u003e (range, 11.8\u0026ndash;39.2 kg/m\u003csup\u003e2\u003c/sup\u003e). Exclusion criteria were prior thoracolumbar surgery, multilevel lumbar spondylolisthesis, retrolisthesis, ossification of the posterior longitudinal ligament, ankylosing spondylitis, and severe scoliosis. The L4\u0026ndash;5 level was selected because it is the most frequently affected single level, prone to instability due to sagittally oriented facet joints and greater gravitational loading compared with other vertebrae[\u003cspan additionalcitationids=\"CR13 CR14\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. The institutional review board approved the study protocol, and written informed consent was obtained from all participants.\u003c/p\u003e\n\u003ch3\u003eRadiographic measures\u003c/h3\u003e\n\u003cp\u003eUpright, flexion, and extension standing radiographs were obtained to evaluate lumbar instability. Before each examination, patients were instructed by the radiology technician to bend forward and backward to the maximum extent possible. Images were acquired using digital X-ray cassettes with a film\u0026ndash;focus distance of 1.15 m.\u003c/p\u003e\u003cp\u003eChanges in lumbar lordosis during forward flexion [ΔLL(flex)] were measured as the difference in lumbar lordosis between upright and flexion positions. Changes during extension [ΔLL(ext)] were determined by comparing extension and upright positions[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Additionally, ST, PO, and SA were also measured on functional radiographs (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). ST was measured according to the method of Dupuis et al. expressed as both absolute values and percentages of the upper vertebral body width[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. PO was measured on flexion radiographs using the method of Luk et al.[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The angle was defined as positive for kyphosis and negative for lordosis. SA was calculated as the difference in intervertebral angles between extension and flexion positions[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eTwo independent raters evaluated each patient\u0026rsquo;s two sets of functional radiographs to measure ΔLL(flex), ΔLL(ext), ST, PO, and SA. Rater A was an experienced spine surgeon with 19 years of clinical practice (T.M.), and Rater B was an orthopedic surgeon with 3 years of experience (T.I.). Intervertebral instability was defined as ST\u0026thinsp;\u0026ge;\u0026thinsp;3 mm or \u0026ge;\u0026thinsp;8% of the upper vertebral body width, PO\u0026thinsp;\u0026ge;\u0026thinsp;5\u0026deg;, or SA\u0026thinsp;\u0026ge;\u0026thinsp;20\u0026deg;[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Consistency of instability diagnosis was analyzed separately for each rater.\u003c/p\u003e\u003cp\u003eIntra-rater reliability was assessed for each rater using ICC(1,1), based on the first and second radiographic sets. Inter-rater reliability was evaluated using ICC(2,1) from the first set of radiographs.\u003c/p\u003e\u003cp\u003eAbsolute reliability was examined with Bland\u0026ndash;Altman analysis for both intra- and inter-rater comparisons[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Bland\u0026ndash;Altman plots and limits of agreement (LoA) were used to assess measurement repeatability and agreement between raters. The minimal detectable change at the 95% confidence level (MDC\u003csub\u003e95\u003c/sub\u003e) was calculated when no fixed or proportional errors were present, representing the smallest measurable difference beyond error. Fixed bias was determined by calculating the 95% confidence interval of the mean difference between measurements, with significance defined as p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 in paired t-tests. Proportional bias was evaluated using the Pearson correlation coefficient (r) between measurement means and differences; a significant correlation (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) indicated proportional bias.\u003c/p\u003e\u003cp\u003eAll statistical analyses were performed using SPSS software (version 30; IBM Corp., Armonk, NY, USA), with statistical significance set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eMeasurement values\u003c/h2\u003e\u003cp\u003eThe values of ΔLL(flex), ΔLL(ext), ST, PO, and SA measured by the two independent raters are shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Both Rater A and Rater B evaluated all 112 cases.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMeasurement values of ΔLL(flex), ΔLL(ext), ST, PO, and SA.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003eRater A\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003eRater B\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1st imaging\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2nd imaging\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1st imaging\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e2nd imaging\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e∆LL(flex)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e13.3\u0026thinsp;\u0026plusmn;\u0026thinsp;9.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e11.7\u0026thinsp;\u0026plusmn;\u0026thinsp;7.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e13.4\u0026thinsp;\u0026plusmn;\u0026thinsp;9.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e13.8\u0026thinsp;\u0026plusmn;\u0026thinsp;7.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e∆LL(ext)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e9.0\u0026thinsp;\u0026plusmn;\u0026thinsp;5.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e9.2\u0026thinsp;\u0026plusmn;\u0026thinsp;5.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e9.5\u0026thinsp;\u0026plusmn;\u0026thinsp;6.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e9.0\u0026thinsp;\u0026plusmn;\u0026thinsp;5.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eST\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e2.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e2.3\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e2.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e2.3\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e-1.5\u0026thinsp;\u0026plusmn;\u0026thinsp;4.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e-1.7\u0026thinsp;\u0026plusmn;\u0026thinsp;4.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e-1.8\u0026thinsp;\u0026plusmn;\u0026thinsp;4.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e-2.0\u0026thinsp;\u0026plusmn;\u0026thinsp;4.0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e4.8\u0026thinsp;\u0026plusmn;\u0026thinsp;2.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e4.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e5.0\u0026thinsp;\u0026plusmn;\u0026thinsp;3.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e5.5\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cp\u003e\u003cem\u003eΔLL(flex)\u003c/em\u003e Change in lumbar lordosis during forward flexion (°), \u003cem\u003eΔLL(ext)\u003c/em\u003e Change in lumbar lordosis during back extension\u0026nbsp;(°), \u003cem\u003eST\u003c/em\u003e Sagittal translation\u0026nbsp;(mm), \u003cem\u003ePO\u003c/em\u003e Posterior opening\u0026nbsp;(°), and \u003cem\u003eSA\u003c/em\u003e Segmental angulation (°).\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003ch3\u003eInstability diagnosis\u003c/h3\u003e\n\u003cp\u003eDiscrepancies in instability diagnosis between the two imaging sessions were observed in 28 cases (25.0%) for Rater A and 31 cases (27.7%) for Rater B (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Consistent diagnoses of instability across both sessions were made in 20 cases (17.9%) by Rater A and 24 cases (21.4%) by Rater B.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\n\u003ch3\u003eIntra-rater reliabilities\u003c/h3\u003e\n\u003cp\u003eIntra-rater reliability results are summarized in Tables\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. For Rater A, ΔLL(flex), ST, and SA demonstrated poor to low reliability [ICC(1,1)\u0026thinsp;=\u0026thinsp;0.23, 0.53, and 0.37, respectively], indicating considerable intra-rater variability. PO showed good reliability [ICC(1,1)\u0026thinsp;=\u0026thinsp;0.76], and ΔLL(ext) demonstrated moderate reliability [ICC(1,1)\u0026thinsp;=\u0026thinsp;0.68]. Similar patterns were observed for Rater B, with ΔLL(flex), ST, and SA demonstrating low reliability [ICC(1,1)\u0026thinsp;=\u0026thinsp;0.32, 0.35, and 0.31, respectively]. Bland\u0026ndash;Altman plots (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) indicated acceptable agreement between repeated measurements of ΔLL(flex) and ST by both raters. The MDC\u003csub\u003e95\u003c/sub\u003e analysis showed the greatest variability in ΔLL(flex).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eIntra-rater reliability of Rater A for the measurements of ΔLL(flex), ΔLL(ext), ST, PO, and SA.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"15\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c15\" colnum=\"15\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" morerows=\"1\" nameend=\"c3\" namest=\"c2\" rowspan=\"2\"\u003e\u003cp\u003eRelative reliability\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"11\" nameend=\"c15\" namest=\"c5\"\u003e\u003cp\u003eAbsolute reliability\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c8\" namest=\"c5\"\u003e\u003cp\u003eFixed error\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e\u003cp\u003eProportional error\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c15\" namest=\"c13\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eICC(1,1)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e95%CI\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMean Diff\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e95%CI\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eT value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003er\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c13\"\u003e\u003cp\u003eSEM\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c14\"\u003e\u003cp\u003eMDC\u003csub\u003e95\u003c/sub\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c15\"\u003e\u003cp\u003eLoA\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e∆LL(flex)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.047〜0.40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1.71\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e-0.29〜3.70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.093\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e0.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.066\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e7.53\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e\u003cp\u003e20.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e\u003cp\u003e-19.2\u0026thinsp;~\u0026thinsp;22.6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e∆LL(ext)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.68\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.57〜0.77\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e-0.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e-1.06〜0.68\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e-0.44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e-0.046\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e3.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e\u003cp\u003e9.09\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e\u003cp\u003e-9.28\u0026thinsp;~\u0026thinsp;8.89\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eST\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.40〜0.66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.096\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e-0.12〜0.31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e-0.059\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.53\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e0.81\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e\u003cp\u003e2.25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e\u003cp\u003e-2.14\u0026thinsp;~\u0026thinsp;2.34\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.76\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.67〜0.83\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e-0.33〜0.84\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e-0.16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e2.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e\u003cp\u003e6.07\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e\u003cp\u003e-5.82\u0026thinsp;~\u0026thinsp;6.34\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.20〜0.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e-0.21〜1.03\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e-0.033\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.73\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e2.34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e\u003cp\u003e6.49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e\u003cp\u003e-6.08\u0026thinsp;~\u0026thinsp;6.91\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cem\u003eICC\u003c/em\u003e Intraclass Correlation Coefficient,\u0026nbsp;\u003cem\u003eCI\u003c/em\u003e Confidence Interval,\u003cem\u003eSEM\u003c/em\u003e Standard Error of Measurement, \u003cem\u003eMean Diff\u003c/em\u003e Mean Difference, \u003cem\u003eLoA\u003c/em\u003e Limits of Agreement, \u003cem\u003eMDC\u003c/em\u003e Minimal detectable change, \u003cem\u003er\u003c/em\u003e Correlation\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eIntra-rater reliability of Rater B for the measurements of ΔLL(flex), ΔLL(ext), ST, PO, and SA.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"15\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c15\" colnum=\"15\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" morerows=\"1\" nameend=\"c3\" namest=\"c2\" rowspan=\"2\"\u003e\u003cp\u003eRelative reliability\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"11\" nameend=\"c15\" namest=\"c5\"\u003e\u003cp\u003eAbsolute reliability\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c8\" namest=\"c5\"\u003e\u003cp\u003eFixed error\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e\u003cp\u003eProportional error\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c15\" namest=\"c13\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eICC(1,1)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e95%CI\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMean Diff\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e95%CI\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eT value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003er\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c13\"\u003e\u003cp\u003eSEM\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c14\"\u003e\u003cp\u003eMDC\u003csub\u003e95\u003c/sub\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c15\"\u003e\u003cp\u003eLoA\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e∆LL(flex)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.15〜0.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e-0.41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e-2.27〜1.44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e-0.44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e0.13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e7.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e\u003cp\u003e19.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e\u003cp\u003e-19.8\u0026thinsp;~\u0026thinsp;19.0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e∆LL(ext)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.69\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.58〜0.78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e-0.46〜1.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.96\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e0.089\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e3.39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e\u003cp\u003e9.40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e\u003cp\u003e-8.95\u0026thinsp;~\u0026thinsp;9.82\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eST\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.17〜0.50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e-0.053〜0.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e-0.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.081\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e1.10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e\u003cp\u003e3.05\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e\u003cp\u003e-2.78\u0026thinsp;~\u0026thinsp;3.26\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.54〜0.75\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e-0.41〜0.88\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.73\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.47\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e0.092\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e2.42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e\u003cp\u003e6.71\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e\u003cp\u003e-6.49\u0026thinsp;~\u0026thinsp;6.96\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.13〜0.46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e-0.49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e-0.21〜1.03\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e-1.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e0.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e2.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e\u003cp\u003e6.99\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e\u003cp\u003e-7.46\u0026thinsp;~\u0026thinsp;6.49\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eInter-rater reliabilities\u003c/h2\u003e\u003cp\u003eInter-rater reliability results are presented in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. Statistical analysis revealed good inter-rater reliability [ICC(2,1)\u0026thinsp;\u0026gt;\u0026thinsp;0.75] for all parameters. SEM values were generally higher than those obtained in the intra-rater analysis. Bland\u0026ndash;Altman analysis demonstrated no fixed or proportional errors, a finding further supported by Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, which showed no systematic bias between raters in ΔLL(flex) and ST measurements from the first imaging. Unlike intra-rater results, ΔLL(flex) demonstrated high inter-rater reliability.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eInter-rater reliability for the measurements of ΔLL(flex), ΔLL(ext), ST, PO, and SA.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"15\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c15\" colnum=\"15\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" morerows=\"1\" nameend=\"c3\" namest=\"c2\" rowspan=\"2\"\u003e\u003cp\u003eRelative reliability\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"11\" nameend=\"c15\" namest=\"c5\"\u003e\u003cp\u003eAbsolute reliability\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c8\" namest=\"c5\"\u003e\u003cp\u003eFixed error\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e\u003cp\u003eProportional error\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c15\" namest=\"c13\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eICC(2,1)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e95%CI\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMean Diff\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e95%CI\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eT value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003er\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c13\"\u003e\u003cp\u003eSEM\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c14\"\u003e\u003cp\u003eMDC\u003csub\u003e95\u003c/sub\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c15\"\u003e\u003cp\u003eLoA\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e∆LL(flex)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.81\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.74〜0.87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e-0.12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e-1.17〜0.94\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e-0.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.83\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e0.058\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.54\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e4.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e\u003cp\u003e11.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e\u003cp\u003e-11.2\u0026thinsp;~\u0026thinsp;11.0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e∆LL(ext)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.72〜0.86\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e-1.16〜0.25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e-1.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e-0.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.076\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e2.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e\u003cp\u003e7.40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e\u003cp\u003e-7.87\u0026thinsp;~\u0026thinsp;6.95\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eST\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.79\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.70〜0.85\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e-0.10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e-0.24〜0.048\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e-1.34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e-0.10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e0.56\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e\u003cp\u003e1.55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e\u003cp\u003e-1.65\u0026thinsp;~\u0026thinsp;1.45\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.83\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.76〜0.88\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e-0.16〜0.77\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e-0.012\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e2.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e\u003cp\u003e7.40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e\u003cp\u003e-4.57\u0026thinsp;~\u0026thinsp;5.17\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.79\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.71〜0.85\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e-0.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e-0.56〜0.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e-0.97\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e-0.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.069\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e1.41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e\u003cp\u003e3.91\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e\u003cp\u003e3.72\u0026thinsp;~\u0026thinsp;4.08\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eDespite multiple randomized trials and meta-analyses, consensus remains lacking on whether decompression alone or decompression with fusion provides superior outcomes for degenerative lumbar spondylolisthesis[\u003cspan additionalcitationids=\"CR23\" citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. This uncertainty is partly attributable to the absence of standardized imaging protocols and evaluation criteria for lumbar instability. The lack of a widely accepted, simple, and reproducible imaging method has hindered the development of statistically validated criteria based on postoperative clinical outcomes and radiographic findings. Currently, parameters such as ST, PO, and SA are used to evaluate lumbar instability. However, studies have demonstrated that these values may be markedly reduced when lumbar flexion is insufficient[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. In conventional standing flexion\u0026ndash;extension radiographs, patients are instructed to bend forward maximally. Nevertheless, many patients\u0026mdash;particularly those experiencing pain or discomfort\u0026mdash;struggle to achieve adequate flexion. In the absence of a defined endpoint, forward bending remains highly variable and dependent on patient effort. Against this backdrop, the present study evaluated the reproducibility and reliability of instability-related parameters derived from standard standing flexion\u0026ndash;extension radiography, the most widely used functional imaging technique worldwide. To our knowledge, this is the first study to comprehensively assess the reliability of functional radiographic evaluations in this context.\u003c/p\u003e\u003cp\u003eIn this study, discrepancies in instability diagnosis between the two imaging sessions were identified in 28 cases (25.0%) by Rater A and in 31 cases (27.7%) by Rater B. Only 20 cases for Rater A and 24 cases for Rater B were consistently classified as unstable in both evaluations. These inconsistencies in diagnosis highlight concerns regarding the reproducibility and diagnostic accuracy of instability assessment using conventional flexion\u0026ndash;extension radiographs. Without reliable evaluation of instability, establishing a sound basis for determining whether decompression alone or decompression with fusion is the appropriate surgical strategy remains difficult. Therefore, before considering surgical options, it is necessary to understand in detail the reproducibility and limitations of the widely used flexion\u0026ndash;extension imaging method.\u003c/p\u003e\u003cp\u003eIntra-rater analysis demonstrated that ΔLL(flex) had poor reliability, with an ICC(1,1) of 0.23 (95% CI: 0.047\u0026ndash;0.40) for Rater A and 0.32 (95% CI: 0.15\u0026ndash;0.48) for Rater B, indicating substantial measurement variability. Similarly, ST showed relatively low ICC(1,1) values of 0.53 for Rater A and 0.35 for Rater B, both insufficient for clinical reliability. In contrast, PO and ΔLL(ext) exhibited good and moderate reliability for Rater A and B. The higher reliability of PO may stem from its calculation based on a single measurement (the intervertebral angle in flexion), whereas parameters such as ΔLL(flex), ST, and SA depend on the difference between two measurements (flexion and extension), which increases compounded variability. The relatively greater reliability of ΔLL(ext) may also reflect the smaller range of motion and reduced pain or fear of falling associated with extension compared with flexion.\u003c/p\u003e\u003cp\u003eFor all parameters, neither fixed nor proportional bias was identified. T values were not statistically significant, and all correlation coefficients (r) were \u0026lt;\u0026thinsp;0.2, indicating that measurement errors were random rather than systematic and that no methodological bias was present in the measurement techniques. Notably, ΔLL(flex) demonstrated extremely wide LoA and large MDC\u003csub\u003e95\u003c/sub\u003e, suggesting that even a difference of approximately 20\u0026deg; may fall within the range of measurement variability.\u003c/p\u003e\u003cp\u003eIn contrast, inter-rater reliability analysis showed high consistency across all parameters. ICC(2,1) values for ΔLL(flex), ΔLL(ext), ST, PO, and SA exceeded 0.75, with narrow and stable 95% confidence intervals. Neither fixed nor proportional bias was identified, and the LoA and MDC\u003csub\u003e95\u003c/sub\u003e ranges were within clinically acceptable limits. These findings suggest that the measurement technique and procedures were well standardized, enabling consistent evaluation across raters.\u003c/p\u003e\u003cp\u003eOf particular importance, although ΔLL(flex) and ST exhibited poor and relatively low intra-rater reliability, they demonstrated high inter-rater reliability. This suggests that the measurement technique is inherently robust and reproducible, and that variability is more likely attributable to patient-related factors\u0026mdash;specifically, inconsistency in reproducing the same degree of flexion, variability in effort, and the absence of clear guidance on the extent of forward bending.\u003c/p\u003e\u003cp\u003eTaken together, these findings indicate that the prevailing method of standing flexion\u0026ndash;extension radiography has limited reliability, with substantial variability across imaging sessions. To establish dependable criteria for surgical decision-making in lumbar spondylolisthesis\u0026mdash;specifically, whether decompression alone is sufficient or fusion is required\u0026mdash;it is essential to develop a functional imaging protocol that incorporates clear, standardized instructions and ensures high reproducibility.\u003c/p\u003e\u003cp\u003eThis study has several limitations. First, the sample size was relatively small. Second, only one flexion and extension radiograph was obtained per session. In addition, patient-reported outcomes such as pain or other patient-centered assessments were not evaluated at the time of imaging.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study demonstrated that instability parameters derived from standing lumbar flexion\u0026ndash;extension radiographs exhibited variable intra-rater reliability, particularly for ΔLL(flex) and ST, whereas inter-rater reliability was consistently high across all parameters. These results suggest that the measurement technique is reproducible, but limitations of the imaging method\u0026mdash;such as inconsistent flexion and the absence of a standardized endpoint\u0026mdash;contribute substantially to variability between sessions. To enhance diagnostic accuracy and guide evidence-based surgical decision-making for lumbar degenerative spondylolisthesis, development of a standardized functional imaging protocol that reduces methodological variability is warranted.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/strong\u003eThe authors did not receive support from any organization for the submitted work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent\u003c/strong\u003e Informed consent was obtained from all individual participants included in the study.\u0026nbsp;\u003c/p\u003e\u003cp\u003e\u003ch2\u003eCompeting interests\u003c/h2\u003e\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eEthics approval\u003c/strong\u003e\u003cp\u003e All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eTM conceptualized and designed the study; TM, AT, RF, SF, and TI collected the data; TM and HT performed the statistical analysis; TM wrote the initial draft of the manuscript; ME helped revise the manuscript; TY supervised this study; and AT performed validation of this study. All authors critically reviewed the manuscript and approved the final version.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eWe thank Izaya Ogon for their assistance while conducting this study and the editors for English language editing.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets generated during and/or analyzed during the current study are not publicly available, but are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eHennemann S, de Abreu MR (2021) Degenerative Lumbar Spinal Stenosis. 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Eur Spine J 32:1054\u0026ndash;1067. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00586-022-07507-1\u003c/span\u003e\u003cspan address=\"10.1007/s00586-022-07507-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGhogawala Z, Dziura J, Butler WE, Dai F, Terrin N, Magge SN, Coumans JV, Harrington JF, Amin-Hanjani S, Schwartz JS, Sonntag VK, Barker FG 2nd, Benzel EC (2016) Laminectomy plus Fusion versus Laminectomy Alone for Lumbar Spondylolisthesis. N Engl J Med 374:1424\u0026ndash;1434. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1056/NEJMoa1508788\u003c/span\u003e\u003cspan address=\"10.1056/NEJMoa1508788\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"european-spine-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"esjo","sideBox":"Learn more about [European Spine Journal](http://link.springer.com/journal/586)","snPcode":"586","submissionUrl":"https://submission.springernature.com/new-submission/586/3","title":"European Spine Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Lumbar, Instability, Spondylolisthesis, Lumbar spinal stenosis, Radiography, Functional imaging","lastPublishedDoi":"10.21203/rs.3.rs-7492640/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7492640/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e\u003cp\u003eSurgical management of lumbar degenerative spondylolisthesis\u0026mdash;whether decompression alone or combined with fusion\u0026mdash;often relies on instability assessment with standing flexion\u0026ndash;extension radiographs. However, these evaluations are influenced by low back pain and other factors, introducing variability into instability determination and surgical planning. Despite widespread use, the reproducibility of quantitative parameters remains unclear. This study evaluated the reproducibility of commonly used quantitative indicators from lumbar functional imaging.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eWe retrospectively analyzed 112 patients with L4\u0026ndash;5 degenerative spondylolisthesis who underwent two sets of standing flexion\u0026ndash;extension radiographs within six months. Five parameters were measured: Changes in lumbar lordosis during flexion [ΔLL(flex)], changes during extension [ΔLL(ext)], sagittal translation (ST), posterior opening (PO), and segmental angulation (SA). Instability was defined as ST\u0026thinsp;\u0026ge;\u0026thinsp;3 mm or \u0026ge;\u0026thinsp;8% of the upper vertebral body width, PO\u0026thinsp;\u0026ge;\u0026thinsp;5\u0026deg;, or SA\u0026thinsp;\u0026ge;\u0026thinsp;20\u0026deg;, and diagnostic consistency was examined. Two raters independently assessed all radiographs. Intra- and inter-rater reliabilities were determined using intraclass correlation coefficients (ICC[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], ICC[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]). Bland\u0026ndash;Altman analysis tested fixed and proportional bias.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eDiagnostic discrepancies between imaging sessions occurred in 25.0\u0026ndash;27.7%. ΔLL(flex) showed poor intra-rater reliability (ICC\u0026thinsp;=\u0026thinsp;0.23, 0.32), whereas ΔLL(ext) and PO demonstrated higher reliability. ST and SA yielded low ICC values. Inter-rater reliability was consistently good (ICC\u0026thinsp;\u0026gt;\u0026thinsp;0.75), and no fixed or proportional bias was detected.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eVariability in flexion influenced ST and SA, potentially affecting instability diagnosis. Standardized imaging protocols and clearer patient instructions are essential to improve diagnostic accuracy and reliability.\u003c/p\u003e","manuscriptTitle":"Accuracy and Reliability of Functional Imaging in Assessing Instability of Lumbar Degenerative Spondylolisthesis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-10 18:58:57","doi":"10.21203/rs.3.rs-7492640/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-09-23T11:12:57+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-14T05:54:13+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-12T17:42:17+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"243020719526557447775423591837758898528","date":"2025-09-12T17:27:43+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-10T15:20:52+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"16343797860177993450934457237589867854","date":"2025-09-09T06:51:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"32016797146500198841387361673430269242","date":"2025-09-06T15:16:14+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-04T05:55:46+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-01T11:14:11+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-09-01T11:11:20+00:00","index":"","fulltext":""},{"type":"submitted","content":"European Spine Journal","date":"2025-08-30T04:21:51+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"european-spine-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"esjo","sideBox":"Learn more about [European Spine Journal](http://link.springer.com/journal/586)","snPcode":"586","submissionUrl":"https://submission.springernature.com/new-submission/586/3","title":"European Spine Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"16df2a02-437e-435c-8a53-8b9d9742581f","owner":[],"postedDate":"September 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-11-10T15:59:11+00:00","versionOfRecord":{"articleIdentity":"rs-7492640","link":"https://doi.org/10.1007/s00586-025-09539-9","journal":{"identity":"european-spine-journal","isVorOnly":false,"title":"European Spine Journal"},"publishedOn":"2025-11-05 15:57:01","publishedOnDateReadable":"November 5th, 2025"},"versionCreatedAt":"2025-09-10 18:58:57","video":"","vorDoi":"10.1007/s00586-025-09539-9","vorDoiUrl":"https://doi.org/10.1007/s00586-025-09539-9","workflowStages":[]},"version":"v1","identity":"rs-7492640","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7492640","identity":"rs-7492640","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}